During many surgical procedures it is necessary to temporarily constrict or occlude the blood flow in blood vessels, such as veins and arteries. This is typically achieved with a surgical clamp comprising a pair of elongate clamping members. A clamping member is positioned either side of the vein or artery, or either side of body tissue comprising the vein or artery, and the clamping members are biased towards each other to hold the vein, artery or body tissue therebetween. Biasing is typically achieved via a spring, a ratcheting mechanism or by hand depending on the type of clamping device and the location of the vein, artery or body tissue being clamped.
Blood vessel clamps, for example, are available from manufacturers in a range of sizes suited to clamping blood vessels ranging from about 0.02 mm to about 2 cm. Some clamps have a pre-set clamping tension for each respective clamp size, while other larger clamps are manually operated using a ratcheting closure system requiring the operator to estimate the appropriate level of force required to occlude blood flow in the blood vessel. Smaller clamps comprise shorter clamping members and smaller springs, which exert a lower clamping force in an effort to avoid damage to the respective blood vessels. Conversely, larger clamps comprise longer clamping members and stronger springs, which exert a higher clamping force to constrict or occlude blood flow in larger blood vessels. Such clamps can be single clamps or a pair of clamps mounted to a rod or pin and spaced apart for clamping two different locations of a single artery.
For some types of surgery, the pair of elongate clamping members is provided at the end of a pair of elongate handles, such as with forceps, such that clamping within a body cavity can be achieved more easily. In this example, the clamping members are typically retained in one of a plurality of predetermined separation positions via a releasable ratchet mechanism.
One disadvantage with the aforementioned prior art clamping devices is that the force exerted on the vein, artery or tissue by the clamping members can vary quite significantly. The ratchet or scissor-type clamps can exert a very high force because of the mechanical advantage the user has when operating them. This will depend on the size and type of clamp used, the size and type of spring or other biasing means employed, the type of vein or artery being clamped and the amount and type of tissue surrounding the vein or artery. For example, muscle has a high tensile strength whereas fat has a low tensile strength. If the force is too low, the desired level of blood flow constriction or occluded blood flow will not be achieved and if the force is too high, the vein or artery could be damaged leading to potentially life-threatening complications. Examples of such complications include thrombosis, which is caused as a result of damage to the blood vessel at the point of clamping, and heart attacks or strokes caused by dislodgement of plaque material at the clamping site.
Often the pressure exerted by the clamping members is non-uniform along their length resulting in a pressure gradient. Many clamps apply greater pressure at the approximate location of the blood vessel being clamped with less pressure being applied at the distal location of the blood vessel causing damage to the blood vessel as a result of uneven pressure being applied to the blood vessel.
Another drawback of conventional surgical clamps and in particular the manually operated clamps that are available in a range of sizes and shapes, is the cost. For example, a batch of 10 surgical clamps of a single size and shape can cost about $500. A single size of clamp may only be suitable for a specific type of surgery and such clamps are often disposable, single-use clamps. Therefore medical facilities experience significant expenditure in providing and maintaining sufficient numbers of clamps in the required range of sizes. Furthermore, a particular size of clamp may be suitable for exerting an appropriate level of force on a particular artery in one patient, but this may be excessive or insufficient for the same artery in the same procedure in a different patient, for example, due to varying levels of plaque build up between patients.
Metal surgical clamping devices can be sterilized and reused, which addresses to an extent the cost associated with replacing single use clamping devices. However, reusable metal surgical clamping devices usually have a greater initial cost. Also, at least some of the metal surgical clamping devices experience metal fatigue after repeated use, which can lead to cracks in the metal that can cause infection. Metal surgical clamps also tend to lose clamping tension due to repeated use.
Various attempts have been made to alleviate at least some of these problems. For example, EP1562492 discloses an apparatus for the detection and occlusion of blood flow comprising a pair of elongate clamping members for clamping tissue comprising an artery. The apparatus is similar to a pair of forceps and comprises a releasable ratcheting mechanism to maintain pressure between the clamping members. One of the clamping members comprises a blood flow detecting sensor to facilitate the location or monitoring of the artery to be occluded. The sensor can detect the reduction or abolition of blood flow and the releasable ratcheting mechanism can be adjusted to change the blood flow.
The apparatus of EP1562492 is particularly suited for occluding blood flow in uterine arteries. However, blood flow is still dependent on and controlled by the manual adjustment of the releasable ratcheting mechanism by the nurse or surgeon, thus still requiring the necessary skill and care in applying the correct pressure for the particular procedure, the particular region of the body and the particular patient. Furthermore, the blood flow detecting sensor is coupled to a sensor control device via a detachable cable external to the elongate arms of the device. The external cable can potentially interfere with the procedure and can present a snagging risk in relation to other apparatus or protruding elements in the operating theatre. Therefore, the external cable is considered to be undesirable. Whilst the elongate arms facilitate access to body cavities, the elongate arms render the clamping apparatus of EP1562492 unusable for many procedures where clamping in confined cavities is required.
Other clamping or occlusion devices are known from the following: US2005/0113634, US2005/0113852, WO2009/048367, U.S. Pat. Nos. 6,582,451, 6,656,205, EP1878390, U.S. Pat. Nos. 4,800,879, 5,921,996, 4,120,302 and 5,697,942. However, at least some of the clamping or occlusion devices in these documents exhibit one or more of the aforementioned problems.
The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.